Scale-Up Device For Testing Bit Balling Characteristics
An apparatus and method for testing the effects of mud chemistry and bit design on bit balling is disclosed The apparatus includes a replica bit coupled to a rotary drive and having at least one nozzle, a test container, a test formation located within the test container through which the replica bit will be drive, wherein the test formation includes a plurality of layers of pre-manufactured cuttings The apparatus further includes a lifting device applying a force to the bottom of the container to drive the test formation into the replica bit while the replica bit is rotating, a second container within which is a drilling fluid, and a pump for communicating drilling fluid from the container through a conduit to the replica bit.
When drilling in earth formations, solid materials such as “cuttings” (i.e., pieces of a formation dislodged by the cutting action of teeth on a drill bit) are produced
BACKGROUND OF INVENTIONWhen drilling in earth formations, solid materials such as “cuttings” (i.e., pieces of a formation dislodged by the cutting action of teeth on a drill bit) are produced.
Bit balling, also known as balling or balling up, refers to the collection of sticky consolidated material, usually drill cuttings, on drill pipe, drill collars, bits, etc. A bit with such material attached to it is often referred to as a “balled-up bit.” Balling up is frequently the result of inadequate hydraulic energy or undesirable interaction between drilling fluid and the cuttings.
Bit balling is one problem that is frequently encountered when drilling through clay. The problem is caused by the tendency of hydrated clay minerals to stick or adhere to the bit and bottom-hole assembly of a drill string. From an operations standpoint, bit balling is evidenced by increased pump pressures as the flow pathway through the well bore annulus becomes blocked, reduced rates of penetration, blocked shaker screens, a required over-pull tension that occurs due to a restricted annulus when tripping pipe, and possible stuck pipe.
Drilling rates can be significantly reduced by bit balling—the unwanted accumulation of reactive drill solids on the drilling surfaces and in the junk slots of the bit. Balling is mitigated by improving drilling fluid characteristics/properties and bit design. Optimization of the combined system in the laboratory can be expensive and time- consuming.
SUMMARYIn one aspect, the claimed subject matter is generally directed to a test apparatus for testing and studying the effects of mud chemistry and bit design on bit balling. The apparatus includes a replica bit coupled to a rotary drive and having at least on nozzle, a test container, a test formation located within the container through which the replica bit will be driven, wherein the test formation includes a plurality of layers of pre-manufactured cuttings. The apparatus further includes a lifting device for applying a force to the bottom of the test container to drive the test formation into the replica bit while the replica bit is rotated by the rotary drive, a second container within which is a drilling fluid, a conduit providing fluid communication from the second container to the replica bit, and a pump for circulating drilling fluid from the second container through the conduit to the replica bit.
In another aspect, the claimed subject matter is generally directed to a method of testing the effects of mud chemistry and bit design on bit balling. The method includes mixing a plurality of mixtures of ground rock material and reactive clay, layering the mixtures into a test container to create a test formation, coupling a replica bit to a rotary drive, fluidly connecting the replica bit to a second container containing drilling fluid, positioning the replica bit within the test container to a position above the test formation, rotating the replica bit, pumping fluid from the container to the replica bit, and lifting the test formation to the rotating replica bit so that the bit rotates into the formation.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
The claimed subject matter relates to a test apparatus 10 for testing the effects of mud chemistry and bit design, hydraulics, weight on bit, and rotary speed on bit balling. Referring to
Referring to
The replica bit 14 is a three-dimensionally printed, plastic model of a PDC bit. Referring to
When assembled into the test apparatus 10, the replica bit 14 drilling fluid is pumped through the replica bit 14 in a manner consistent with a full-sized PDC bit in a drilling environment. The nozzles 28 are in fluid communication with a conduit directing fluid into the bit. Drilling fluid is communicated towards the test formation 16 through the nozzles 28.
The test formation 16 includes pre-manufactured cuttings 32 made from ground rock material blended with predetermined concentrations of reactive clay and compressed for proper consistency. The distribution of particle sizes and formation characteristics are selected to simulate that achieved under actual drilling conditions. Referring again to
Continuing to refer to
Referring to
The test container 18 is preferably cylindrical to represent the wellbore walls, although it may have other cross sectional shapes. The test container 18 may be transparent so that the test can be viewed and/or recorded by an external camera. When an external camera is to be used, the inner diameter of the test container 18 must be larger than the outer diameter of the replica bit 14 but not so much larger that the bit performance cannot be easily viewed through the container. It is noted, however, that if an external camera is not being used, the test container 18 need not be transparent.
The test container 18 may be retained such that it is able to rotate slightly with increasing torque. That is, as the replica bit 14 is rotated into the simulated formation, some amount of resistance may be transferred to the test container 18. The test container 18 may be provided with a torsion spring or similar mechanism to allow the test container 18 to rotate a relatively small amount, such as less than 25°.
The test container 18 containing the test formation 16 is lifted towards the replica bit 14 as the test is conducted. This may be performed by a lifting device 20, such as an air or hydraulic cylinder, located beneath the test container 18 or by another mechanism, such as a pulley system or rack and pinion, for example. Any device to lift the container relative to the longitudinally stationary replica bit 14 may suffice. This configuration advantageously allows a camera to be placed in a stationary location outside of the test container 18 and to capture bit performance. Alternatively, the test container 18 may be held longitudinally stationary while the replica bit 14 is driven rotationally into the simulated formation.
When the test formation 16 is created and testing is to begin, the replica bit 14 is coupled directly or indirectly to the rotary drive 12 and located within the test container 18 above the test formation 16. As previously discussed, a camera 26 may be used to document the test. Testing can be videotaped for documentation and detailed review. Referring to
As testing is conducted sensors may be used to measure data that may be collected by a computer 46 and displayed on a monitor. Alternatively, data may be collected by another data collection device. Referring to
Referring to
Use of “pre-manufactured cuttings” instead of a solid rock sample allows use of printed, plastic, small-diameter replica bits. Test formations can consist of ground rock material blended with specific concentrations of reactive clay compressed to the proper consistency for testing. Bits can be coated with metallic materials to simulate the surface of actual bits. Testing can be conducted with different fluid designs. Equipment capable of calculating mechanical specific energy to aid in evaluation.
Applicants have found that balling achieved with the device is very similar to that encountered in the field. It is expected that effects of changing mud chemistry and bit design can be completed efficiently and cost-effectively by use of this equipment and procedure. Bit designs and fluids historically tested independently, or using expensive, time-consuming test equipment. See Paper SPE114673-MS, Bit Balling Mitigation in PDC Bit Design, by Michael Wells, PLUERE, Inc.; Tim Marvel and Chad Beuershausen, Hughes Christensen, IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, 25-27 Aug. 2008, Jakarta, Indonesia
Advantageously, the use of pre-manufactured cuttings provides consistently sized cuttings. By having the cuttings a consistent size, a formation can be precisely formulated. Further, formations can be repeatably formulated which allows a better comparison of bit designs. Additionally, bits “printed” on a 3-Dimensional printer from a 3-Dimensional CAD drawing can be used to easily check new bit designs.
While the claimed subject matter has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the claimed subject matter as disclosed herein. Accordingly, the scope of the claimed subject matter should be limited only by the attached claims.
Claims
1. An apparatus for testing the effects of mud chemistry and bit design on bit balling comprising:
- a replica bit coupled to a rotary drive and having at least one nozzle;
- a test container;
- a test formation located within the container, wherein the test formation includes: a plurality of layers of pre-manufactured cuttings;
- a lifting device applying a force to the bottom of the test container to drive the test formation into the replica bit while the replica bit is rotated by the rotary drive;
- a second container within which is a drilling fluid;
- a conduit providing fluid communication from the second container to the replica bit; and
- a pump for circulating drilling fluid from the second container through the conduit to the replica bit.
2. The apparatus of claim 1 further comprising a camera focused on the replica bit.
3. The apparatus of claim 1, wherein the test container is transparent, and further comprising a camera located outside of the test container, wherein the camera is focused on the replica bit inside the test container.
4. The apparatus of claim 1 further comprising a computer including inputs to track test parameters, wherein the test parameters include at least one of time, torque on the replica bit, rotary speed, and position of the replica bit relative to the bottom of the test formation.
5. The apparatus of claim 4, wherein the computer is used to calculate at least one of weight on bit, rate of penetration, and mechanical specific energy.
6. The apparatus of claim 1, wherein the pre-manufactured cuttings comprise ground rock material and reactive clay.
7. The apparatus of claim 6, wherein the ground rock material is selected from the group consisting of shale, marble, a combination of shale and marble.
8. The apparatus of claim 1, wherein the replica bit is a three-dimensionally printed, plastic model of a PDC bit.
9. The apparatus of claim 8, wherein the replica bit is coated with a metallic finish.
10. A method of testing the effects of mud chemistry and bit design on bit balling comprising:
- mixing a plurality of mixtures of ground rock material and reactive clay;
- layering the mixtures into a test container to create a test formation;
- coupling a replica bit to a rotary drive;
- fluidly connecting the replica bit to a second container containing drilling fluid;
- positioning the replica bit within the test container to a position above the test formation;
- rotating the replica bit;
- pumping fluid from the container and through the replica bit; and
- lifting the test formation to the rotating replica bit so that the bit rotates into the formation.
11. The method of claim 10, further comprising:
- layering the mixtures into the test container such that the first layer loaded into the container has a lower concentration of reactive clay than the next successive layer and each successive layer has a higher concentration of reactive clay than the previous layer.
12. The method of claim 10, further comprising:
- layering the mixtures into the test container such that the first layer loaded into the container has a higher concentration of reactive clay than the next successive layer and each successive layer has a lower concentration of reactive clay than the previous layer.
13. The method of claim 10, wherein the mixtures are layered to create a formation with varied layers.
14. The method of claim 10, wherein the mixtures are layered to create a formation with homogenous layers.
15. The method of claim 10 further comprising measuring test parameters;
- wherein the test parameters include at least one of time, torque on the replica bit, rotary speed, and position of the replica bit relative to the bottom of the test formation.
16. The method of claim 15 further comprising calculating at least one of rate of penetration, weight on bit, and mechanical specific energy.
17. The method of claim 10 further comprising using a camera to video the replica bit as it is rotated through the formation.
18. The method of claim 10 further comprising using a camera to take pictures of the replica bit as it is rotated through the formation.
Type: Application
Filed: Mar 10, 2010
Publication Date: Jun 21, 2012
Inventors: Mario Zamora (Houston, TX), Marian Baranowski (Houston, TX), Kenneth Slater (Sealy, TX)
Application Number: 13/393,124
International Classification: E21B 47/00 (20120101);